ci(py): drop macos-13 x86_64 wheel target

GitHub-hosted macos-13 runners are deprecated and now queue for hours
or indefinitely, blocking the Release job (which `needs: [..., macos]`)
and stalling PyPI publishes. Apple Silicon is the dominant Mac arch
since 2020; shipping only aarch64 macOS wheels is the pragmatic move.

Author: davidsmfreire

.github/workflows/ci.yml

@@ -124,8 +124,9 @@ jobs:
     strategy:
       matrix:
         platform:
-          - runner: macos-13
-            target: x86_64
+          # macos-13 (Intel) hosted runners are deprecated and queue
+          # indefinitely. Apple Silicon is the dominant Mac arch, so
+          # we ship only aarch64 wheels.
           - runner: macos-14
             target: aarch64
     steps: